1. Field of the Invention
The present invention relates to a method of displaying velocities and pressures in a display device for injection molding, wherein the state of injection velocities and injection pressures of a resin material is displayed as waveforms along with conditions established for injection molding.
2. Detailed Description of the Prior Art
As one of the prior art methods of displaying velocities and pressures, a method is known wherein
a display screen is divided into a left-hand portion and a right-hand portion by a vertical axis disposed at the center of the display screen,
the left-hand portion of the display screen serves as a time axis display screen having a time scale,
the right-hand portion of the display screen serves as a position axis display screen having a position scale,
the above-mentioned vertical axis disposed at the center of the display screen serves as a line of demarcation representing a pressure-holding switchover point,
velocities and/or pressures produced in conjunction with the shifting of positions of an injection screw are displayed during a filling process, and
velocities and/or pressures produced in conjunction with the lapse of time are graphically displayed during a pressure-holding process.
In the case of the method of display mentioned immediately above:
during the injection process, velocities and/or pressures which are produced as the injection screw travels forward from the extreme right of the position axis display screen to the pressure-holding switchover point thereon can be continuously displayed as waveforms; and
during the pressure-holding process, velocities and/or pressures which are produced as time elapses from the initiation of pressure-holding to the completion thereof, the point of the above-mentioned completion being locates at the extreme left of the time axis display screen.
subsequent to pressure-holding switchover, velocities and/or pressures produced in conjunction with the forward travel of the injection screw from the pressure-holding switchover point to the pressure-holding completion point cannot be displayed, since no display is carried out by means of the position scale.
Normally, switchover from injection to pressure-holding is carried out at a position short of the mechanical forward travel limit of the injection screw. Even after the above-mentioned switchover takes place, the injection screw moves in response to pressure-holding switchover and contraction of resin injected into and filled inside a cavity, the above-mentioned contraction being caused by cooling. Even subsequent to the above-mentioned switchover, it is regarded as necessary that velocities and pressures be displayed by means of a position scale up to the position at which pressure-holding is completed, in order that changes in velocities and pressures in the early stage of pressure-holding may be ascertained, thereby carrying out injection without any trouble.
This being so, in the case of a new prior art method:
the display screen is divided into a left-hand portion and a right-hand portion with the screw forward travel limit as the borderline,
the left-hand portion serving as a time axis display screen,
the right-hand portion serving as a position axis display screen;
velocities and/or pressures during a pressure-holding process are displayed as waveforms on the time axis display screen, with the screw forward travel limit as the pressure-holding initiation point;
the pressure-holding switchover point is displayed on the position axis display screen, at a position short of the screw forward travel limit point; and
as a consequence, even velocities and/or pressures produced subsequent to holding-pressure switchover can be displayed as waveforms by means of a position scale.
However, in the case of this new prior art method, velocities and/or pressures on the time axis display screen are displayed with the screw forward travel limit point as the pressure-holding initiation point. Therefore, the velocities and/or pressures as displayed on the time axis display screen are limited to those produced subsequent to the initiation of pressure-holding, and thus the state of current pressures as they were prior to the initiation of pressure-holding cannot be displayed as waveforms on the time axis display screen. This being so, the state of current pressures as they were prior to the initiation of pressure-holding is confirmed through observation of current pressures as they were in a range short of the pressure-holding point on the position axis display screen.
To sum up, the problems with prior art methods are as follows.
If the arrangement is such that velocities and/or pressures are continuously displayed as waveforms both on the position scale and on the time scale, then velocities and/or pressures produced between the holding-pressure switchover point and a point subsequent to the completion of holding-pressure cannot be displayed as waveforms by means of the position scale.
And if the holding-pressure switchover point is displayed at a position short of the screw forward travel limit with the aim of enabling the above, then the continuity of waveforms as displayed is lost, thus rendering it difficult to ascertain the state of pressures as they are prior and subsequent to the initiation of pressure holding.
A holding-pressure switchover point is generally defined as a control point at which filling velocity control performed so far is switched over to pressure control. Since a holding-pressure switchover point is essentially a point at which velocity control is switched over to pressure control, the above-mentioned control point is referred as a V-P switchover point in the present invention. Smooth operation is required at this V-P switchover point, and it is regarded as undesirable from the viewpoint of stable molding if any drastic pressure or velocity is present at the V-P switchover point.
The present invention was contrived with the aim of solving the above-mentioned problems with prior art methods. It is an object of the present invention to provide a new method of displaying velocities and pressures in a display device for injection molding, wherein by displaying a V-P switchover point as a vertical axis in each of a position axis display screen and of a time axis display screen, not only can velocities and pressures subsequent to V-P switchover be displayed as waveforms on the position axis display screen, but also the state of velocities and pressures prior to V-P switchover can be displayed as waveforms on the time axis display screen.
The present invention, whose object is as described above, comprises:
a time axis display screen for displaying velocities and/or pressures with a horizontal axis as a time scale; and
a position axis display screen for displaying velocities and/or pressures with a horizontal axis as a position scale;
the above-mentioned time axis display screen and the above-mentioned position axis display screen being disposed side by side on a display panel surface along with fields for various numerical values established as molding conditions: wherein
a V-P switchover point is displayed as a vertical axis in each of the above-mentioned position axis display screen and of the above-mentioned time axis display screen;
the above-mentioned time axis display screen is divided into a left-hand portion and a right-hand portion by the vertical axis representing the above-mentioned V-P switchover point;
the state of velocities and pressures subsequent to V-P switchover is continuously displayed as waveforms on the above-mentioned time axis display screen, starting at a time prior to V-P switchover; and
the ratio at which the above-mentioned time axis display screen is divided by the above-mentioned vertical axis representing V-P switchover point can be changed arbitrarily.